The compounds that cause this situation can be traced to algae that grows in all of the Great Lakes. The algae and other microorganisms give off compounds that are powerful in the taste and odor effect they produce.
It is believed this effect on the water is more noticeable due to the pesky zebra mussel now found in the Great Lakes. Each mussel filters about one liter of water each day. This has improved the clarity of the lakes which, in turn, help the sun’s rays to penetrate deeper which, in turn, helps the algae and microorganisms to grow.
Filtration and chemicals such as chlorine and activated carbon help eliminate most of the problems.